[11] CAUSE OF THE GREENING OF OYSTERS. 803 



kowski and Eostafluski). When the crushed plants are treated with 

 strong alcohol, after the extraction of the blue pigment, a green solu- 

 tion is obtained, which contains true chlorophyll, and probably a special 

 yellow pigment, phycoxanthin (Millardet and Kraus)." The group of 

 phycocyan and phycoerythrine vegetable pigments, according to H. 

 C Sorby, give remarkable spectra with one main absorption band. 



I have failed to prove by spectroscopic research that the substance 

 which tinges the oyster is chlorophyll. In fact I have been unable to 

 obtain alcoholic solutions of this substance from green oysters which 

 were apparently dense enough to give a spectrum, and light, which had 

 been transmitted through a mass of the green blood-cells, also failed to 

 show any absorption bands. Dessication destroys the bluish-green color 

 In Navicida ostrearia, according to Puys^gur, and it is significant in this 

 connection that Sorby found that the Phycocyanin group of pigments 

 were also associated with albuminous substances somewhat in the same 

 way as hcemoglobin in the blood, being, like the latter, decomposed at 

 exactly the same temperature as that at which albumen coagulates. 

 My own view may therefore be expressed as follows : That the coloring 

 material in green oysters, on account of its solubility in water, its in- 

 stability and color, is probably allied to Phycocyanin, since we know 

 that it is not chlorophyll, because the latter is insoluble in water, 

 meanwhile remembering that the spectroscope also gave us entirely 

 negative evidence ui>on this point. 



The diffuse bluish coloring matters of Stentor coertileus and Freia are 

 also interesting in this connection. The detection of vegetable algous 

 parasites in the fresh-water mussel by Leidy is a case of an entirely 

 different nature, from the condition of things found in green-fleshed 

 oysters, yet it is interesting as an illustration of animal and vegetable 

 symbiosis. 



The most searching tests which I made for the detection of the pres- 

 ence of green vegetable parasites in the oyster, as I at one time sup- 

 posed, have given negative results, and I think that in the presence of 

 all the foregoing evidence the phenomenon can be in no sense due to 

 symbiosis, but rather to a tinging of the blood cells by an unstable col- 

 oring matter, which has been dissolved out of the food, and which in 

 this case is derived from a diatom, in the more fluid plasma of which it 

 exists in much the same relation to the latter as the haemoglobin found 

 in the blood corpuscles of vertebrates, or the coloring matters which 

 tinge the blood of Cephalopods, or those of some of the Arcldw, but not 

 forming, as in them, a normal portion of their substance. 



The coloring matter, however, in the case of the oyster when absorbed 

 from its vegetable source produces certain abnormal changes in those 

 blood-cells which imbibe it, as is conclusively shown by the facts which 

 we have related regarding the accumulation of the tinged corpuscles in 

 cysts of an abnormal character, as well as in the heart. Yet this effect * 

 is clearly unlike that produced by inert staining fluids, such as are used 



